WO2016048095A2

WO2016048095A2 - Method and apparatus for transmitting reception acknowledgement signal in wireless access system supporting machine type communication

Info

Publication number: WO2016048095A2
Application number: PCT/KR2015/010219
Authority: WO
Inventors: 김봉회; 이윤정
Original assignee: 엘지전자 주식회사
Priority date: 2014-09-25
Filing date: 2015-09-25
Publication date: 2016-03-31
Also published as: WO2016048095A3

Abstract

The present invention relates to a wireless access system supporting machine type communication (MTC). According to an embodiment of the present invention, a method of an MTC terminal transmitting a reception acknowledgement signal (HARQ-ACK) in a wireless access system supporting MTC may comprise the steps of: monitoring a physical downlink control channel (PDCCH) in a monitoring section consisting of N subframes; receiving one or more PDCCHs from the N subframes; and transmitting HARQ-ACK with respect to all the subframes included in the monitoring section in the x^th subframe after the subframe in which a monitoring section is finished.

Description

Method and apparatus for transmitting acknowledgment signal in wireless access system supporting machine type communication

The present invention relates to a wireless access system supporting Machine Type Communication (MTC), and various methods for transmitting and receiving a hybrid automatic retransmission reQeust (HARQ) acknowledgment signal and apparatuses for supporting the same. It is about.

Wireless access systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless access system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access) system.

An object of the present invention is to provide various methods for supporting reliable data transmission in a wireless access system supporting MTC.

Another object of the present invention is to provide methods for setting the number of HARQ processes for MTC terminal.

Another object of the present invention is to provide a method of coding a HARQ-ACK bit transmitted by an MTC terminal.

Still another object of the present invention is to provide a method for allocating resources for transmitting HARQ-ACK by an MTC terminal.

Still another object of the present invention is to provide a method for adjusting power for transmitting an uplink control channel by an MTC terminal.

It is yet another object of the present invention to provide devices which support these methods.

Technical objects to be achieved in the present invention are not limited to the above-mentioned matters, and other technical problems which are not mentioned are those skilled in the art from the embodiments of the present invention to be described below. Can be considered.

The present invention relates to a wireless access system supporting machine type communication (MTC), and provides various methods for transmitting and receiving a HARQ-ACK and apparatuses for supporting the same.

In one aspect of the present invention, a method for transmitting an acknowledgment signal (HARQ-ACK) by the MTC terminal in a radio access system supporting machine type communication (MTC), the physical downlink control channel in the monitoring interval consisting of N subframes Monitoring (PDCCH), receiving at least one PDCCH in N subframes, and transmitting HARQ-ACK for all subframes included in the monitoring interval in the xth subframe after the subframe in which the monitoring interval ends. It may include the step.

In another aspect of the present invention, an MTC terminal for transmitting an acknowledgment signal (HARQ-ACK) in a radio access system supporting machine type communication (MTC) is functionally connected to a transmitter, a receiver, and such a transmitter and a receiver to perform HARQ-ACK. It may include a processor configured to transmit. At this time, the processor monitors the physical downlink control channel (PDCCH) in the monitoring interval consisting of N subframes; Control the receiver in the N subframes to receive at least one PDCCH; It may be configured to control and transmit the HARQ-ACK for all the subframes included in the monitoring interval in the x-th subframe after the monitoring interval is terminated.

In embodiments of the invention, N and x are integers of 1 or greater.

In this case, the HARQ-ACK is configured with ACK or NACK information on a received physical downlink shared channel (PDSCH) in a subframe in which at least one PDCCH is received, and NACK for a subframe in which at least one PDCCH is not received. HARQ-ACK may be configured with information.

The method further includes receiving a higher layer signal including information on the size N of the monitoring interval, wherein the number of HARQ processes for the MTC terminal may be set in consideration of the size N of the monitoring interval. Can be.

One or more HARQ-ACKs may be transmitted through a physical uplink control channel (PUCCH) format 3, and only a single carrier may be allocated to the MTC terminal.

At this time, if the PDCCH is transmitted in the last subframe of the monitoring interval, one or more HARQ-ACK may be transmitted through the resources of the physical uplink control channel (PUCCH) inferred based on the CCE information on the PDCCH.

Alternatively, if the PDCCH is not transmitted in the last subframe of the monitoring interval, one or more HARQ-ACKs may be transmitted through a physical uplink control channel (PUCCH) configured by a higher layer.

The above-described aspects of the present invention are merely some of the preferred embodiments of the present invention, and various embodiments reflecting the technical features of the present invention will be described in detail by those skilled in the art. Based on the description, it can be derived and understood.

According to embodiments of the present invention has the following effects.

First, in a wireless access system supporting MTC, it is possible to support reliable data transmission while minimizing power consumption of the MTC terminal.

Second, by resetting the number of HARQ processes for the MTC terminal, the MTC terminal can efficiently transmit and receive data.

Third, by providing a method of coding a HARQ-ACK bit transmitted by the MTC terminal, a method of allocating resources for transmitting the HARQ-ACK, and a method of adjusting power for transmitting an uplink control channel, It can support to transmit the HARQ-ACK at the power of.

Effects obtained in the embodiments of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are usually described in the technical field to which the present invention pertains from the description of the embodiments of the present invention. Can be clearly derived and understood by those who have That is, unintended effects of practicing the present invention may also be derived from those skilled in the art from the embodiments of the present invention.

It is included as part of the detailed description to assist in understanding the present invention, and the accompanying drawings provide various embodiments of the present invention. In addition, the accompanying drawings are used to describe embodiments of the present invention in conjunction with the detailed description.

1 is a diagram illustrating a physical channel and a signal transmission method using the same.

2 is a diagram illustrating an example of a structure of a radio frame.

3 is a diagram illustrating a resource grid for a downlink slot.

4 is a diagram illustrating an example of a structure of an uplink subframe.

5 is a diagram illustrating an example of a structure of a downlink subframe.

FIG. 6 shows

PUCCH formats

1a and 1b in the case of general cyclic prefix, and FIG. 7 shows

PUCCH formats

1a and 1b in the case of extended cyclic prefix.

FIG. 8 shows PUCCH format 2 / 2a / 2b in case of general cyclic prefix, and FIG. 9 shows PUCCH format 2 / 2a / 2b in case of extended cyclic prefix.

10 is a diagram illustrating ACK / NACK channelization for

PUCCH formats

1a and 1b.

FIG. 11 illustrates channelization for a mixed structure of PUCCH formats 1a / 1b and 2 / 2a / 2b in the same PRB.

12 is a diagram illustrating PRB allocation.

FIG. 13 is a diagram illustrating an example of carrier aggregation used in a component carrier (CC) and LTE_A system used in embodiments of the present invention.

14 illustrates a subframe structure of an LTE-A system according to cross carrier scheduling used in embodiments of the present invention.

15 is a diagram illustrating an example of a configuration of a serving cell according to cross carrier scheduling used in embodiments of the present invention.

16 is a diagram illustrating a signal processing procedure of CA PUCCH.

17 illustrates an example of a new PUCCH format based on block spreading.

18 is a diagram for explaining dual RM coding.

19 is a diagram for describing a method of interleaving output bits output through a dual RM coder.

20 is a diagram for describing HARQ-ACK transmission timing by an MTC terminal.

The apparatus described in FIG. 21 is a means in which the methods described in FIGS. 1 to 20 may be implemented.

The present invention relates to a wireless access system supporting machine type communication (MTC), and provides various methods for transmitting and receiving HARQ-ACK and devices supporting the same.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps which may obscure the gist of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Throughout the specification, when a part is said to "comprising" (or including) a component, this means that it may further include other components, except to exclude other components unless specifically stated otherwise. do. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have. Also, "a or an", "one", "the", and the like are used differently in the context of describing the present invention (particularly in the context of the following claims). Unless otherwise indicated or clearly contradicted by context, it may be used in the sense including both the singular and the plural.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a mobile station in a network consisting of a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.

Further, in embodiments of the present invention, a terminal may be a user equipment (UE), a mobile station (MS), a subscriber station (SS), or a mobile subscriber station (MSS). It may be replaced with terms such as a mobile terminal or an advanced mobile station (AMS).

Also, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the IEEE 802.xx system, the 3rd Generation Partnership Project (3GPP) system, the 3GPP LTE system, and the 3GPP2 system, which are wireless access systems, and in particular, the present invention. Embodiments of the may be supported by 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321 and 3GPP TS 36.331 documents. That is, obvious steps or portions not described among the embodiments of the present invention may be described with reference to the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the invention may be practiced.

In addition, specific terms used in the embodiments of the present invention are provided to help the understanding of the present invention, and the use of the specific terms may be changed into other forms without departing from the technical spirit of the present invention. .

For example, the term Transmission Opportunity Period (TxOP) may be used in the same meaning as the term transmission period or RRP (Reserved Resource Period). Also, the List Before Talk (LBT) process may be performed for the same purpose as the carrier sensing process for determining whether the channel state is idle.

Hereinafter, a 3GPP LTE / LTE-A system will be described as an example of a wireless access system in which embodiments of the present invention can be used.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be applied to various radio access systems.

CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA).

UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. The LTE-A (Advanced) system is an improved system of the 3GPP LTE system. In order to clarify the description of the technical features of the present invention, embodiments of the present invention will be described based on the 3GPP LTE / LTE-A system, but can also be applied to IEEE 802.16e / m system and the like.

1. 3GPP LTE/LTE_A 시스템1.3GPP LTE / LTE_A System

In a wireless access system, a terminal receives information from a base station through downlink (DL) and transmits information to the base station through uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist according to the type / use of the information they transmit and receive.

1.1 시스템 일반1.1 System General

1 is a diagram for explaining physical channels that can be used in embodiments of the present invention and a signal transmission method using the same.

When the power is turned off again or a new cell enters the cell, the initial cell search operation such as synchronizing with the base station is performed in step S11. To this end, the UE receives a Primary Synchronization Channel (P-SCH) and a Secondary Synchronization Channel (S-SCH) from the base station, synchronizes with the base station, and obtains information such as a cell ID.

Thereafter, the terminal may receive a physical broadcast channel (PBCH) signal from the base station to obtain broadcast information in a cell.

On the other hand, the terminal may receive a downlink reference signal (DL RS) in the initial cell search step to confirm the downlink channel state.

After completing the initial cell search, the UE receives a physical downlink control channel (PDCCH) and a physical downlink control channel (PDSCH) according to the physical downlink control channel information in step S12. Specific system information can be obtained.

Subsequently, the terminal may perform a random access procedure as in steps S13 to S16 to complete the access to the base station. To this end, the UE transmits a preamble through a physical random access channel (PRACH) (S13), a response message to the preamble through a physical downlink control channel and a corresponding physical downlink shared channel. Can be received (S14). In case of contention-based random access, the UE may perform contention resolution such as transmitting an additional physical random access channel signal (S15) and receiving a physical downlink control channel signal and a corresponding physical downlink shared channel signal (S16). Procedure).

After performing the above-described procedure, the UE subsequently receives a physical downlink control channel signal and / or a physical downlink shared channel signal (S17) and a physical uplink shared channel (PUSCH) as a general uplink / downlink signal transmission procedure. A transmission (Uplink Shared Channel) signal and / or a Physical Uplink Control Channel (PUCCH) signal may be transmitted (S18).

The control information transmitted from the terminal to the base station is collectively referred to as uplink control information (UCI). UCI includes Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK (HARQ-ACK / NACK), Scheduling Request (SR), Channel Quality Indication (CQI), Precoding Matrix Indication (PMI), and Rank Indication (RI). .

In the LTE system, UCI is generally transmitted periodically through the PUCCH, but may be transmitted through the PUSCH when control information and traffic data should be transmitted at the same time. In addition, the UCI may be aperiodically transmitted through the PUSCH by the request / instruction of the network.

2 shows a structure of a radio frame used in embodiments of the present invention.

2 (a) shows a frame structure type 1. The type 1 frame structure can be applied to both full duplex Frequency Division Duplex (FDD) systems and half duplex FDD systems.

One radio frame has a length of Tf = 307 200 * Ts = 10 ms, an equal length of Tslot = 15360 * Ts = 0.5 ms, and consists of 20 slots indexed from 0 to 19. One subframe is defined as two consecutive slots, and the i-th subframe includes slots corresponding to 2i and 2i + 1. That is, a radio frame consists of 10 subframes. The time taken to transmit one subframe is called a transmission time interval (TTI). Here, Ts represents a sampling time and is represented by T _s = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns). The slot includes a plurality of OFDM symbols or SC-FDMA symbols in the time domain and a plurality of resource blocks in the frequency domain.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. Since 3GPP LTE uses OFDMA in downlink, the OFDM symbol is for representing one symbol period. The OFDM symbol may be referred to as one SC-FDMA symbol or symbol period. A resource block is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot.

In a full-duplex FDD system, 10 subframes may be used simultaneously for downlink transmission and uplink transmission during each 10ms period. At this time, uplink and downlink transmission are separated in the frequency domain. On the other hand, in the case of a half-duplex FDD system, the terminal cannot simultaneously transmit and receive.

The structure of the radio frame described above is just one example, and the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of OFDM symbols included in the slot may be variously changed.

2 (b) shows a frame structure type 2. Type 2 frame structure is applied to the TDD system. One radio frame has a length of Tf = 307200 * Ts = 10ms and consists of two half-frames having a length of 153600 * Ts = 5ms. Each half frame consists of five subframes having a length of 30720 * Ts = 1ms. The i-th subframe consists of two slots each having a length of Tslot = 15360 * Ts = 0.5ms corresponding to 2i and 2i + 1. Here, Ts represents a sampling time and is represented by T _s = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns).

The type 2 frame includes a special subframe consisting of three fields: a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). Here, the DwPTS is used for initial cell search, synchronization or channel estimation in the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

Table 1 below shows the structure of the special frame (length of DwPTS / GP / UpPTS).

Table 1

3 is a diagram illustrating a resource grid for a downlink slot that can be used in embodiments of the present invention.

Referring to FIG. 3, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, one downlink slot includes seven OFDM symbols, and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element on the resource grid is a resource element, and one resource block includes 12 × 7 resource elements. The number NDL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth. The structure of the uplink slot may be the same as the structure of the downlink slot.

4 shows a structure of an uplink subframe that can be used in embodiments of the present invention.

Referring to FIG. 4, an uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is allocated a PUCCH carrying uplink control information. In the data area, a PUSCH carrying user data is allocated. In order to maintain a single carrier characteristic, one UE does not simultaneously transmit a PUCCH and a PUSCH. The PUCCH for one UE is allocated an RB pair in a subframe. RBs belonging to the RB pair occupy different subcarriers in each of the two slots. The RB pair assigned to this PUCCH is said to be frequency hopping at the slot boundary.

5 shows a structure of a downlink subframe that can be used in embodiments of the present invention.

Referring to FIG. 5, up to three OFDM symbols from the OFDM symbol index 0 in the first slot in the subframe are control regions to which control channels are allocated, and the remaining OFDM symbols are data regions to which the PDSCH is allocated. to be. One example of a downlink control channel used in 3GPP LTE includes a Physical Control Format Indicator Channel (PCFICH), a PDCCH, and a Physical Hybrid-ARQ Indicator Channel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols (ie, the size of the control region) used for transmission of control channels within the subframe. The PHICH is a response channel for the uplink and carries an ACK (Acknowledgement) / NACK (Negative-Acknowledgement) signal for a hybrid automatic repeat request (HARQ). Control information transmitted through the PDCCH is called downlink control information (DCI). The downlink control information includes uplink resource allocation information, downlink resource allocation information or an uplink transmission (Tx) power control command for a certain terminal group.

1.2 PDCCH(Physical Downlink Control Channel)1.2 Physical Downlink Control Channel (PDCCH)

1.2.1 PDCCH 일반1.2.1 PDCCH General

The PDCCH includes resource allocation and transmission format (ie, DL-Grant) of downlink shared channel (DL-SCH) and resource allocation information (ie, uplink grant (UL-) of uplink shared channel (UL-SCH). Grant)), paging information on a paging channel (PCH), system information on a DL-SCH, and an upper-layer control message such as a random access response transmitted on a PDSCH. It may carry resource allocation, a set of transmission power control commands for individual terminals in a certain terminal group, information on whether Voice over IP (VoIP) is activated or the like.

A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs. The PDCCH consists of an aggregation of one or several consecutive control channel elements (CCEs). The PDCCH composed of one or several consecutive CCEs may be transmitted through the control region after subblock interleaving. CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to a state of a radio channel. The CCE corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.

1.2.2 PDCCH 구조1.2.2 PDCCH Structure

A plurality of multiplexed PDCCHs for a plurality of terminals may be transmitted in a control region. The PDCCH is composed of one or more consecutive CCE aggregations (CCE aggregation). CCE refers to a unit corresponding to nine sets of REGs consisting of four resource elements. Four Quadrature Phase Shift Keying (QPSK) symbols are mapped to each REG. Resource elements occupied by a reference signal (RS) are not included in the REG. That is, the total number of REGs in the OFDM symbol may vary depending on whether a cell specific reference signal exists. The concept of REG, which maps four resource elements to one group, can also be applied to other downlink control channels (eg, PCFICH or PHICH). If REG not assigned to PCFICH or PHICH is N _REG , the number of CCEs available in the system is N _CCE = floor (N _REG / 9), and each CCE has an index from 0 to N _CCE -1.

In order to simplify the decoding process of the UE, the PDCCH format including n CCEs may start with a CCE having an index equal to a multiple of n. That is, when the CCE index is i, it may start from a CCE satisfying imod (n) = 0.

The base station may use {1, 2, 4, 8} CCEs to configure one PDCCH signal, wherein {1, 2, 4, 8} is called a CCE aggregation level. The number of CCEs used for transmission of a specific PDCCH is determined by the base station according to the channel state. For example, one CCE may be sufficient for a PDCCH for a terminal having a good downlink channel state (close to the base station). On the other hand, in case of a UE having a bad channel state (when it is at a cell boundary), eight CCEs may be required for sufficient robustness. In addition, the power level of the PDCCH may also be adjusted to match the channel state.

Table 2 below shows a PDCCH format, and four PDCCH formats are supported as shown in Table 2 according to the CCE aggregation level.

TABLE 2

PDCCH Format	CCE Count (n)	REG Count	PDCCH Bit Count
0	One	9	72
One	2	18	144
2	4	36	288
3	8	72	576

The reason why the CCE aggregation level is different for each UE is because a format or a modulation and coding scheme (MCS) level of control information carried on the PDCCH is different. The MCS level refers to a code rate and a modulation order used for data coding. Adaptive MCS levels are used for link adaptation. In general, three to four MCS levels may be considered in a control channel for transmitting control information.

Referring to the format of the control information, control information transmitted through the PDCCH is referred to as downlink control information (DCI). According to the DCI format, the configuration of information carried in the PDCCH payload may vary. The PDCCH payload means an information bit. Table 3 below shows DCI according to DCI format.

TABLE 3

DCI format	Contents
Format
0	Resource grants for PUSCH transmissions (uplink)
Format 1	Resource assignments for single codeword PDSCH transmission ( transmission modes 1, 2 and 7)
Format 1A	Compact signaling of resource assignments for sigle codeword PDSCH (all modes)
Format 1B	Compact resource assignments for PDSCH using rank-1 closed loop precoding (mode 6)
Format 1C	Very compact resource assignments for PDSCH (eg, paging / broadcast system information)
Format 1D	Compact resource assignments for PDSCH using multi-user MIMO (mode 5)
Format 2	Resource assignments for PDSCH for closed loop MIMO operation (mode 4)
Format 2A	resource assignments for PDSCH for open loop MIMO operation (mode 3)
Format 3 / 3A	Power control commands for PUCCH and PUSCH with 2-bit / 1-bit power adjustment
Format
4	Scheduling of PUSCH in one UL cell with multi-antenna port transmission mode

Referring to Table 3, a DCI format includes a format 0 for PUSCH scheduling, a format 1 for scheduling one PDSCH codeword, a format 1A for compact scheduling of one PDSCH codeword, and a very much DL-SCH. Format 1C for simple scheduling, format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, for uplink channel There are formats 3 and 3A for the transmission of Transmission Power Control (TPC) commands. DCI format 1A may be used for PDSCH scheduling, regardless of which transmission mode is configured for the UE.

The PDCCH payload length may vary depending on the DCI format. In addition, the type and length thereof of the PDCCH payload may vary depending on whether it is a simple scheduling or a transmission mode set in the terminal.

The transmission mode may be configured for the UE to receive downlink data through the PDSCH. For example, the downlink data through the PDSCH may include scheduled data, paging, random access response, or broadcast information through BCCH. Downlink data through the PDSCH is related to the DCI format signaled through the PDCCH. The transmission mode may be set semi-statically to the terminal through higher layer signaling (eg, RRC (Radio Resource Control) signaling). The transmission mode may be classified into single antenna transmission or multi-antenna transmission.

The terminal is set to a semi-static transmission mode through higher layer signaling. For example, multi-antenna transmission includes transmit diversity, open-loop or closed-loop spatial multiplexing, and multi-user-multiple input multiple outputs. ) Or beamforming. Transmit diversity is a technique of increasing transmission reliability by transmitting the same data in multiple transmit antennas. Spatial multiplexing is a technology that allows high-speed data transmission without increasing the bandwidth of the system by simultaneously transmitting different data from multiple transmit antennas. Beamforming is a technique of increasing the signal to interference plus noise ratio (SINR) of a signal by applying weights according to channel conditions in multiple antennas.

The DCI format is dependent on a transmission mode configured in the terminal (depend on). The UE has a reference DCI format that monitors according to a transmission mode configured for the UE. The transmission mode set in the terminal may have ten transmission modes as follows.

(1) transmission mode 1: single antenna port; Port 0

(2) Transmission Mode 2: Transmit Diversity

(3) Transmission Mode 3: Open-loop Spatial Multiplexing

(4) Transmission Mode 4: Closed-loop Spatial Multiplexing

(5) Transmission Mode 5: Multi-User MIMO

(6) Transmission mode 6: closed loop, rank = 1 precoding

(7) Transmission mode 7: Precoding supporting single layer transmission not based on codebook

(8) Transmission mode 8: Precoding supporting up to two layers not based on codebook

(9) Transmission mode 9: Precoding supporting up to eight layers not based on codebook

(10) Transmission mode 10: precoding supporting up to eight layers, used for CoMP, not based on codebook

1.2.3 PDCCH 전송1.2.3 PDCCH Transmission

The base station determines the PDCCH format according to the DCI to be transmitted to the terminal, and attaches a CRC (Cyclic Redundancy Check) to the control information. In the CRC, a unique identifier (for example, a Radio Network Temporary Identifier (RNTI)) is masked according to an owner or a purpose of the PDCCH. If it is a PDCCH for a specific terminal, a unique identifier (eg, C-RNTI (Cell-RNTI)) of the terminal may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier (eg, P-RNTI (P-RNTI)) may be masked to the CRC. If the system information, more specifically, the PDCCH for the System Information Block (SIB), a system information identifier (eg, a System Information RNTI (SI-RNTI)) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE.

Subsequently, the base station performs channel coding on the control information added with the CRC to generate coded data. In this case, channel coding may be performed at a code rate according to the MCS level. The base station performs rate matching according to the CCE aggregation level allocated to the PDCCH format, modulates the coded data, and generates modulation symbols. At this time, a modulation sequence according to the MCS level can be used. The modulation symbols constituting one PDCCH may have one of 1, 2, 4, and 8 CCE aggregation levels. Thereafter, the base station maps modulation symbols to physical resource elements (CCE to RE mapping).

1.2.4 블라인드 디코딩(BS: Blind Decoding)1.2.4 Blind Decoding (BS)

A plurality of PDCCHs may be transmitted in one subframe. That is, the control region of one subframe includes a plurality of CCEs having indices 0 to N _{CCE, k} −1. Here, N _{CCE, k} means the total number of CCEs in the control region of the kth subframe. The UE monitors the plurality of PDCCHs in every subframe. Here, monitoring means that the UE attempts to decode each of the PDCCHs according to the monitored PDCCH format.

In the control region allocated in the subframe, the base station does not provide information on where the PDCCH corresponding to the UE is. In order to receive the control channel transmitted from the base station, the UE cannot know where the PDCCH is transmitted in which CCE aggregation level or DCI format. Therefore, the UE monitors the aggregation of PDCCH candidates in a subframe. Find the PDCCH. This is called blind decoding (BD). Blind decoding refers to a method in which a UE de-masks its UE ID in a CRC portion and then checks the CRC error to determine whether the corresponding PDCCH is its control channel.

In the active mode, the UE monitors the PDCCH of every subframe in order to receive data transmitted to the UE. In the DRX mode, the UE wakes up in the monitoring interval of every DRX cycle and monitors the PDCCH in a subframe corresponding to the monitoring interval. A subframe in which PDCCH monitoring is performed is called a non-DRX subframe.

In order to receive the PDCCH transmitted to the UE, the UE must perform blind decoding on all CCEs present in the control region of the non-DRX subframe. Since the UE does not know which PDCCH format is transmitted, it is necessary to decode all PDCCHs at the CCE aggregation level possible until blind decoding of the PDCCH is successful in every non-DRX subframe. Since the UE does not know how many CCEs the PDCCH uses for itself, the UE should attempt detection at all possible CCE aggregation levels until the blind decoding of the PDCCH succeeds.

In the LTE system, a search space (SS) concept is defined for blind decoding of a terminal. The search space means a PDCCH candidate set for the UE to monitor and may have a different size according to each PDCCH format. The search space may include a common search space (CSS) and a UE-specific / dedicated search space (USS).

In the case of the common search space, all terminals can know the size of the common search space, but the terminal specific search space can be set individually for each terminal. Accordingly, the UE must monitor both the UE-specific search space and the common search space in order to decode the PDCCH, thus performing a maximum of 44 blind decoding (BDs) in one subframe. This does not include blind decoding performed according to different CRC values (eg, C-RNTI, P-RNTI, SI-RNTI, RA-RNTI).

Due to the limitation of the search space, the base station may not be able to secure the CCE resources for transmitting the PDCCH to all the terminals to transmit the PDCCH in a given subframe. This is because resources remaining after the CCE location is allocated may not be included in the search space of a specific UE. A terminal specific hopping sequence may be applied to the starting point of the terminal specific search space to minimize this barrier that may continue to the next subframe.

Table 4 shows the sizes of the common search space and the terminal specific search space.

Table 4

PDCCH Format	CCE Count (n)	Candidate count in CSS	Candidate Count in USS
0	One	-	6
One	2	-	6
2	4	4	2
3	8	2	2

In order to reduce the load of the UE according to the number of blind decoding attempts, the UE does not simultaneously perform searches according to all defined DCI formats. Specifically, the terminal always performs a search for DCI formats 0 and 1A in the terminal specific search space (USS). In this case, the DCI formats 0 and 1A have the same size, but the UE may distinguish the DCI formats by using a flag used for distinguishing the DCI formats 0 and 1A included in the PDCCH. In addition, a DCI format other than DCI format 0 and DCI format 1A may be required for the UE. Examples of the DCI formats include 1, 1B, and 2.

In the common search space (CSS), the UE may search for DCI formats 1A and 1C. In addition, the UE may be configured to search for DCI format 3 or 3A, and DCI formats 3 and 3A have the same size as DCI formats 0 and 1A, but the UE uses a CRC scrambled by an identifier other than the UE specific identifier. The DCI format can be distinguished.

Search space

Set level

PDCCH candidate set according to the. The CCE according to the PDCCH candidate set m of the search space may be determined by Equation 1 below.

Equation 1

Here, M ^(L) represents the number of PDCCH candidates according to CCE aggregation level L for monitoring in search space,

to be. i is an index designating an individual CCE in each PDCCH candidate in the PDCCH, and i = 0, ..., L-1.

N _s represents a slot index in a radio frame.

As described above, the UE monitors both the UE-specific search space and the common search space to decode the PDCCH. Here, the common search space (CSS) supports PDCCHs having an aggregation level of {4, 8}, and the UE specific search space (USS) supports PDCCHs having an aggregation level of {1, 2, 4, 8}. . Table 5 shows PDCCH candidates monitored by the UE.

Table 5

Referring to Equation 1, Y _k is set to 0 for two aggregation levels, L = 4 and L = 8 for a common search space. On the other hand, for the UE-specific search space for the aggregation level L, Y _k is defined as in Equation 2.

Equation 2

here,

And n _RNTI represents an RNTI value. Further, A = 39827 and D = 65537.

1.3 PUCCH(Physical Uplink Control Channel)1.3 PUCCH (Physical Uplink Control Channel)

PUCCH includes the following format for transmitting control information.

(1) Format 1: On-Off Keying (OOK) Modulation, Used for Scheduling Request (SR)

(2) Format 1a and Format 1b: used for ACK / NACK transmission

1) Format 1a: BPSK ACK / NACK for one codeword

2) Format 1b: QPSK ACK / NACK for 2 codewords

(3) Format 2: QPSK modulation, used for CQI transmission

(4) Format 2a and Format 2b: used for simultaneous transmission of CQI and ACK / NACK

(5) Format 3: Used for transmitting multiple ACK / NACK in CA environment

Table 6 shows a modulation scheme and the number of bits per subframe according to the PUCCH format. Table 7 shows the number of reference signals per slot according to the PUCCH format. Table 8 is a table showing the SC-FDMA symbol position of the reference signal according to the PUCCH format. In Table 6, PUCCH formats 2a and 2b correspond to a case of general cyclic prefix.

Table 6

TABLE 7

Table 8

FIG. 6 shows PUCCH formats 1a and 1b in the case of general cyclic prefix, and FIG. 7 shows PUCCH formats 1a and 1b in the case of extended cyclic prefix.

In

PUCCH formats

1a and 1b, control information having the same content is repeated in a slot unit in a subframe. In each terminal, the ACK / NACK signal includes a cyclic shift (CS) (frequency domain code) and an orthogonal cover code (OC / OCC) of a computer-generated constant amplitude zero auto correlation (CG-CAZAC) sequence. It is transmitted through different resources consisting of orthogonal cover codes (time domain spreading codes). OC includes, for example, Walsh / DFT orthogonal code. If the number of CSs is six and the number of OCs is three, a total of 18 terminals may be multiplexed in the same PRB (Physical Resource Block) based on a single antenna. Orthogonal sequences w0, w1, w2, w3 can be applied in any time domain (after FFT modulation) or in any frequency domain (before FFT modulation).

For SR and persistent scheduling, ACK / NACK resources composed of CS, OC, and PRB (Physical Resource Block) may be given to the UE through RRC (Radio Resource Control). For dynamic ACK / NACK and non-persistent scheduling, ACK / NACK resources may be implicitly given to the UE by the lowest CCE index of the PDCCH corresponding to the PDSCH.

Table 9 shows an orthogonal sequence (OC) of length 4 for PUCCH format 1 / 1a / 1b. Table 10 shows an orthogonal sequence (OC) of length 3 for PUCCH format 1 / 1a / 1b.

Table 9

Table 10

Table 11 shows an orthogonal sequence (OC) for RS in PUCCH formats 1a / 1b.

Indicates.

Table 11

8 and 9, in the case of a standard CP, one subframe includes 10 QPSK data symbols in addition to the RS symbol. Each QPSK symbol is spread in the frequency domain by the CS and then mapped to the corresponding SC-FDMA symbol. SC-FDMA symbol level CS hopping may be applied to randomize inter-cell interference. RS can be multiplexed by CDM using cyclic shift. For example, assuming that the number of available CSs is 12 or 6, 12 or 6 terminals may be multiplexed in the same PRB, respectively. In short, a plurality of terminals in PUCCH formats 1 / 1a / 1b and 2 / 2a / 2b may be multiplexed by CS + OC + PRB and CS + PRB, respectively.

10 is a diagram illustrating ACK / NACK channelization for PUCCH formats 1a and 1b. 10 is

Corresponds to

Cyclic Shift (CS) hopping and Orthogonal Cover (OC) remapping may be applied as follows.

(1) Symbol-Based Cell-Specific CS Hopping for Randomization of Inter-cell Interference

(2) slot-level CS / OC remapping

1) for inter-cell interference randomization

2) Slot based access for mapping between ACK / NACK channel and resource (k)

Meanwhile, the resource n _r for PUCCH formats 1a / 1b includes the following combination.

(1) CS (= same as DFT orthogonal code at symbol level) (n _cs )

(2) OC (orthogonal cover at slot level) (n _oc )

(3) Frequency RB (Resource Block) (n _rb )

When the indices representing CS, OC, and RB are n _cs , n _oc , and n _rb , respectively, the representative index n _r includes n _cs , n _oc , n _rb . n _{r satisfies} n _r = (n _cs , n _oc , n _rb ).

CQI, PMI, RI, and a combination of CQI and ACK / NACK may be delivered through PUCCH format 2 / 2a / 2b. Reed Muller (RM) channel coding may be applied.

For example, channel coding for UL CQI in an LTE system is described as follows. The bit streams a ₀ , a ₁ , a ₂ , a ₃ , ..., a _A-1 are channel coded using the (20, A) RM code. Here, a ₀ and a _A-1 represent a Most Significant Bit (MSB) and a Least Significant Bit (LSB). In the case of the extended CP, the maximum information bit is 11 bits except when the CQI and the ACK / NACK are simultaneously transmitted. After coding with 20 bits using the RM code, QPSK modulation can be applied. Prior to QPSK modulation, the coded bits may be scrambled.

Table 12 shows a basic sequence for the (20, A) code.

Table 12

The channel coding bits b ₀ , b ₁ , b ₂ , b ₃ , ..., b _B-1 may be generated by Equation 3 below.

Equation 3

Where i = 0, 1, 2,... Satisfies B-1.

In case of wideband reports, the bandwidth of the Uplink Control Information (UCI) field for CQI / PMI is shown in Tables 13 to 15 below.

Table 13 shows the UCI field for CQI feedback in case of wideband reporting (single antenna port, transmit diversity or open loop spatial multiplexing PDSCH transmission).

Table 13

field	Bandwidth
Broadband CQI
	4

Table 14 shows the UCI fields for CQI and PMI feedback in case of wideband reporting (closed loop spatial multiplexing PDSCH transmission).

Table 14

field	Bandwidth
	2 antenna ports		4 antenna ports
	rank = 1	rank = 2	rank = 1	Rank> 1
Wideband CQI	4	4	4	4
Space Difference CQI	0	3	0	3
Precoding Matrix Instruction	2	One	4	4

Table 15 shows the UCI field for RI feedback in case of wideband reporting.

Table 15

field	Bandwidth
	2 antenna ports	4 antenna ports
		Up to 2 layers	Up to 4 layers
Rank indicator	One	One	2

12 is a diagram illustrating PRB allocation. As shown in FIG. 12, the PRB may be used for PUCCH transmission in slot n _s .

2. 캐리어 병합(CA: Carrier Aggregation) 환경 2. Carrier Aggregation (CA) Environment

2.1 CA 일반2.1 CA General

3GPP LTE (3rd Generation Partnership Project Long Term Evolution (Rel-8 or Rel-9) system (hereinafter referred to as LTE system) is a multi-carrier modulation (MCM) that divides a single component carrier (CC) into multiple bands. Multi-Carrier Modulation) is used. However, in the 3GPP LTE-Advanced system (hereinafter, LTE-A system), a method such as Carrier Aggregation (CA) may be used in which one or more component carriers are combined to support a wider system bandwidth than the LTE system. have. Carrier aggregation may be replaced with the words carrier aggregation, carrier matching, multi-component carrier environment (Multi-CC) or multicarrier environment.

In the present invention, the multi-carrier means the aggregation of carriers (or carrier aggregation), wherein the aggregation of carriers means not only merging between contiguous carriers but also merging between non-contiguous carriers. In addition, the number of component carriers aggregated between downlink and uplink may be set differently. The case where the number of downlink component carriers (hereinafter referred to as 'DL CC') and the number of uplink component carriers (hereinafter referred to as 'UL CC') is the same is called symmetric merging. This is called asymmetric merging. Such carrier aggregation may be used interchangeably with terms such as carrier aggregation, bandwidth aggregation, spectrum aggregation, and the like.

Carrier aggregation, in which two or more component carriers are combined, aims to support up to 100 MHz bandwidth in an LTE-A system. When combining one or more carriers having a bandwidth smaller than the target band, the bandwidth of the combining carrier may be limited to the bandwidth used by the existing system to maintain backward compatibility with the existing IMT system.

For example, the existing 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHz bandwidth, and the 3GPP LTE-advanced system (i.e., LTE-A) supports the above for compatibility with the existing system. Only bandwidths can be used to support bandwidths greater than 20 MHz. In addition, the carrier aggregation system used in the present invention may support carrier aggregation by defining a new bandwidth regardless of the bandwidth used in the existing system.

In addition, the carrier aggregation may be divided into an intra-band CA and an inter-band CA. Intra-band carrier merging means that a plurality of DL CCs and / or UL CCs are located adjacent to or in proximity to frequency. In other words, it may mean that the carrier frequencies of the DL CCs and / or UL CCs are located in the same band. On the other hand, an environment far from the frequency domain may be referred to as an inter-band CA. In other words, it may mean that the carrier frequencies of the plurality of DL CCs and / or UL CCs are located in different bands. In this case, the terminal may use a plurality of radio frequency (RF) terminals to perform communication in a carrier aggregation environment.

The LTE-A system uses the concept of a cell to manage radio resources. The carrier aggregation environment described above may be referred to as a multiple cell environment. A cell is defined as a combination of a downlink resource (DL CC) and an uplink resource (UL CC), but the uplink resource is not an essential element. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources.

For example, when a specific UE has only one configured serving cell, it may have one DL CC and one UL CC. However, when a specific terminal has two or more configured serving cells, it may have as many DL CCs as the number of cells and the number of UL CCs may be the same or smaller than that. Alternatively, the DL CC and the UL CC may be configured on the contrary. That is, when a specific UE has a plurality of configured serving cells, a carrier aggregation environment in which a UL CC has more than the number of DL CCs may be supported.

Carrier coupling (CA) may also be understood as the merging of two or more cells, each having a different carrier frequency (center frequency of the cell). The term 'cell' in terms of carrier combining is described in terms of frequency, and should be distinguished from 'cell' as a geographical area covered by a commonly used base station. Hereinafter, the above-described intra-band carrier merging is referred to as an intra-band multi-cell, and inter-band carrier merging is referred to as an inter-band multi-cell.

Cells used in the LTE-A system include a primary cell (PCell: Primary Cell) and a secondary cell (SCell: Secondary Cell). P cell and S cell may be used as a serving cell. In case of the UE that is in the RRC_CONNECTED state but the carrier aggregation is not configured or does not support the carrier aggregation, there is only one serving cell composed of the PCell. On the other hand, in case of a UE in RRC_CONNECTED state and carrier aggregation is configured, one or more serving cells may exist, and the entire serving cell includes a PCell and one or more SCells.

Serving cells (P cell and S cell) may be configured through an RRC parameter. PhysCellId is a cell's physical layer identifier and has an integer value from 0 to 503. SCellIndex is a short identifier used to identify an SCell and has an integer value from 1 to 7. ServCellIndex is a short identifier used to identify a serving cell (P cell or S cell) and has an integer value from 0 to 7. A value of 0 is applied to the Pcell, and SCellIndex is pre-assigned to apply to the Scell. That is, a cell having the smallest cell ID (or cell index) in ServCellIndex becomes a P cell.

P cell refers to a cell operating on a primary frequency (or primary CC). The UE may be used to perform an initial connection establishment process or to perform a connection re-establishment process, and may also refer to a cell indicated in a handover process. In addition, the P cell refers to a cell serving as a center of control-related communication among serving cells configured in a carrier aggregation environment. That is, the terminal may receive and transmit a PUCCH only in its own Pcell, and may use only the Pcell to acquire system information or change a monitoring procedure. E-UTRAN (Evolved Universal Terrestrial Radio Access) changes only the Pcell for the handover procedure by using an RRC ConnectionReconfigutaion message of a higher layer including mobility control information to a UE supporting a carrier aggregation environment. It may be.

The S cell may refer to a cell operating on a secondary frequency (or, secondary CC). Only one PCell may be allocated to a specific UE, and one or more SCells may be allocated. The SCell is configurable after the RRC connection is established and can be used to provide additional radio resources. PUCCH does not exist in the remaining cells excluding the P cell, that is, the S cell, among the serving cells configured in the carrier aggregation environment.

When the E-UTRAN adds the SCell to the UE supporting the carrier aggregation environment, the E-UTRAN may provide all system information related to the operation of the related cell in the RRC_CONNECTED state through a dedicated signal. The change of the system information may be controlled by the release and addition of the related SCell, and at this time, an RRC connection reconfigutaion message of a higher layer may be used. The E-UTRAN may perform dedicated signaling having different parameters for each terminal, rather than broadcasting in the related SCell.

After the initial security activation process begins, the E-UTRAN may configure a network including one or more Scells in addition to the Pcells initially configured in the connection establishment process. In the carrier aggregation environment, the Pcell and the SCell may operate as respective component carriers. In the following embodiments, the primary component carrier (PCC) may be used in the same sense as the PCell, and the secondary component carrier (SCC) may be used in the same sense as the SCell.

Figure 13 (a) shows a single carrier structure used in the LTE system. Component carriers include a DL CC and an UL CC. One component carrier may have a frequency range of 20 MHz.

13 (b) shows a carrier aggregation structure used in the LTE_A system. 6 (b) shows a case where three component carriers having a frequency size of 20 MHz are combined. Although there are three DL CCs and three UL CCs, the number of DL CCs and UL CCs is not limited. In case of carrier aggregation, the UE may simultaneously monitor three CCs, receive downlink signals / data, and transmit uplink signals / data.

If N DL CCs are managed in a specific cell, the network may allocate M (M ≦ N) DL CCs to the UE. In this case, the UE may monitor only M limited DL CCs and receive a DL signal. In addition, the network may assign L (L ≦ M ≦ N) DL CCs to allocate a main DL CC to the UE, in which case the UE must monitor the L DL CCs. This method can be equally applied to uplink transmission.

The linkage between the carrier frequency (or DL CC) of the downlink resource and the carrier frequency (or UL CC) of the uplink resource may be indicated by a higher layer message or system information such as an RRC message. For example, a combination of DL resources and UL resources may be configured by a linkage defined by SIB2 (System Information Block Type2). Specifically, the linkage may mean a mapping relationship between a DL CC on which a PDCCH carrying a UL grant is transmitted and a UL CC using the UL grant, and a DL CC (or UL CC) and HARQ ACK on which data for HARQ is transmitted. It may mean a mapping relationship between UL CCs (or DL CCs) through which a / NACK signal is transmitted.

2.2 크로스 캐리어 스케줄링(Cross Carrier Scheduling)2.2 Cross Carrier Scheduling

In a carrier aggregation system, there are two types of a self-scheduling method and a cross carrier scheduling method in terms of scheduling for a carrier (or carrier) or a serving cell. Cross carrier scheduling may be referred to as Cross Component Carrier Scheduling or Cross Cell Scheduling.

Self-scheduling is transmitted through a DL CC in which a PDCCH (DL Grant) and a PDSCH are transmitted in the same DL CC, or a PUSCH transmitted according to a PDCCH (UL Grant) transmitted in a DL CC is linked to a DL CC in which a UL Grant has been received. It means to be.

In cross-carrier scheduling, a DL CC in which a PDCCH (DL Grant) and a PDSCH are transmitted to different DL CCs, or a UL CC in which a PUSCH transmitted according to a PDCCH (UL Grant) transmitted in a DL CC is linked to a DL CC having received an UL grant This means that it is transmitted through other UL CC.

Whether to perform cross-carrier scheduling may be activated or deactivated UE-specifically and may be known for each UE semi-statically through higher layer signaling (eg, RRC signaling).

When cross-carrier scheduling is activated, a carrier indicator field (CIF: Carrier Indicator Field) indicating a PDSCH / PUSCH indicated by the corresponding PDCCH is transmitted to the PDCCH. For example, the PDCCH may allocate PDSCH resource or PUSCH resource to one of a plurality of component carriers using CIF. That is, when the PDCCH on the DL CC allocates PDSCH or PUSCH resources to one of the multi-aggregated DL / UL CC, CIF is set. In this case, the DCI format of LTE Release-8 may be extended according to CIF. In this case, the set CIF may be fixed as a 3 bit field or the position of the set CIF may be fixed regardless of the DCI format size. In addition, the PDCCH structure (same coding and resource mapping based on the same CCE) of LTE Release-8 may be reused.

On the other hand, if the PDCCH on the DL CC allocates PDSCH resources on the same DL CC or PUSCH resources on a single linked UL CC, CIF is not configured. In this case, the same PDCCH structure (same coding and resource mapping based on the same CCE) and DCI format as in LTE Release-8 may be used.

When cross carrier scheduling is possible, the UE needs to monitor the PDCCHs for the plurality of DCIs in the control region of the monitoring CC according to the transmission mode and / or bandwidth for each CC. Therefore, it is necessary to configure the search space and PDCCH monitoring that can support this.

In the carrier aggregation system, the terminal DL CC set represents a set of DL CCs scheduled for the terminal to receive a PDSCH, and the terminal UL CC set represents a set of UL CCs scheduled for the terminal to transmit a PUSCH. In addition, the PDCCH monitoring set represents a set of at least one DL CC that performs PDCCH monitoring. The PDCCH monitoring set may be the same as the terminal DL CC set or may be a subset of the terminal DL CC set. The PDCCH monitoring set may include at least one of DL CCs in the terminal DL CC set. Alternatively, the PDCCH monitoring set may be defined separately regardless of the UE DL CC set. The DL CC included in the PDCCH monitoring set may be configured to always enable self-scheduling for the linked UL CC. The UE DL CC set, the UE UL CC set, and the PDCCH monitoring set may be configured UE-specifically, UE group-specifically, or cell-specifically.

When cross-carrier scheduling is deactivated, it means that the PDCCH monitoring set is always the same as the UE DL CC set. In this case, an indication such as separate signaling for the PDCCH monitoring set is not necessary. However, when cross-carrier scheduling is activated, it is preferable that a PDCCH monitoring set is defined in the terminal DL CC set. That is, in order to schedule PDSCH or PUSCH for the UE, the base station transmits the PDCCH through only the PDCCH monitoring set.

Referring to FIG. 14, three DL component carriers (DL CCs) are combined in a DL subframe for an LTE-A terminal, and DL CC 'A' represents a case in which a PDCCH monitoring DL CC is configured. If CIF is not used, each DL CC may transmit a PDCCH for scheduling its PDSCH without CIF. On the other hand, when the CIF is used through higher layer signaling, only one DL CC 'A' may transmit a PDCCH for scheduling its PDSCH or PDSCH of another CC using the CIF. At this time, DL CCs 'B' and 'C' that are not configured as PDCCH monitoring DL CCs do not transmit the PDCCH.

In a radio access system supporting carrier combining (CA), a base station and / or terminals may be composed of one or more serving cells. In FIG. 15, the base station may support a total of four serving cells, such as A cell, B cell, C cell, and D cell, and terminal A is composed of A cell, B cell, and C cell, and terminal B is B cell, C cell, and the like. It is assumed that the D cell and the terminal C is configured as a B cell. In this case, at least one of the cells configured in each terminal may be configured as a P cell. In this case, the PCell is always in an activated state, and the SCell may be activated or deactivated by the base station and / or the terminal.

The cell configured in FIG. 15 is a cell capable of adding a cell to a CA based on a measurement report message from a terminal among cells of a base station, and may be configured for each terminal. The configured cell reserves the resources for the ACK / NACK message transmission for the PDSCH signal transmission in advance. An activated cell is a cell configured to transmit a real PDSCH signal and / or a PUSCH signal among configured cells, and performs CSI reporting and SRS (Sounding Reference Signal) transmission. A de-activated cell is a cell configured not to transmit or receive a PDSCH / PUSCH signal by a command or timer operation of a base station, and also stops CSI reporting and SRS transmission.

2.3 CA PUCCH (Carrier Aggregation Physical Uplink Control Channel)2.3 CA Aggregation Physical Uplink Control Channel (CA PUCCH)

In a wireless communication system supporting carrier aggregation, a PUCCH format for feeding back a UCI (eg, multiple ACK / NACK bits) may be defined. Hereinafter, for convenience of description, the format of this PUCCH is referred to as a CA PUCCH format.

16 is a diagram illustrating a signal processing procedure of CA PUCCH.

Referring to FIG. 16, a channel coding block includes information bits a_0, a_1,... , a_M-1 (e.g., multiple ACK / NACK bits) by channel coding coding bits (encoded bit, coded bit or coding bit) (or codeword) b_0, b_1,... , b_N-1 is generated. M represents the size of the information bits, and N represents the size of the coding bits. The information bits include uplink control information (UCI), for example, multiple ACK / NACKs for a plurality of data (or PDSCHs) received via a plurality of downlink component carriers. Where information bits a_0, a_1,... , a_M-1 is joint coded regardless of the type / number / size of the UCI constituting the information bits. For example, if an information bit includes multiple ACK / NACKs for a plurality of downlink component carriers, channel coding is not performed for each downlink component carrier and for each individual ACK / NACK bit, but for all bit information. From this, a single codeword is generated. Channel coding includes, but is not limited to, simple repetition, simple coding, Reed Muller (RM) coding, punctured RM coding, tail-biting convolutional coding (TBCC), low-density parity- check) or turbo-coding. Although not shown, coding bits may be rate-matched in consideration of modulation order and resource amount. The rate matching function may be included as part of the channel coding block or may be performed through a separate function block.

The modulator comprises coding bits b_0, b_1,... modulates the modulation symbols c_0, c_1,... Create c_L-1. L represents the size of the modulation symbol. The modulation method is performed by modifying the magnitude and phase of the transmission signal. Modulation methods include, for example, Phase Shift Keying (n-PSK) and Quadrature Amplitude Modulation (n-QAM) (n is an integer of 2 or more). Specifically, the modulation method may include Binary PSK (BPSK), Quadrature PSK (QPSK), 8-PSK, QAM, 16-QAM, 64-QAM, and the like.

The divider divides the modulation symbols c_0, c_1,... , c_L-1 is divided into slots. The order / pattern / method for dividing a modulation symbol into each slot is not particularly limited. For example, the divider may divide a modulation symbol into each slot in order from the front (local type). In this case, as shown, modulation symbols c_0, c_1,... , c_L / 2-1 is divided into slot 0, and modulation symbols c_L / 2, c_L / 2 + 1,... , c_L-1 may be divided into slot 1. In addition, the modulation symbols can be interleaved (or permutated) upon dispensing into each slot. For example, an even numbered modulation symbol may be divided into slot 0 and an odd numbered modulation symbol may be divided into slot 1. The modulation process and the dispensing process can be reversed.

A spreading block spreads the divided modulation symbols at the SC-FDMA symbol level (time domain). Time-domain spreading at the SC-FDMA symbol level is performed using a spreading code (or spreading sequence). The spreading code includes a quasi-orthogonal code and an orthogonal code. Quasi-orthogonal codes include, but are not limited to, Pseudo Noise (PN) codes. Orthogonal codes include, but are not limited to, Walsh codes, DFT codes. Orthogonal Code (OC) may be mixed with an orthogonal sequence, an Orthogonal Cover (OC) and an Orthogonal Cover Code (OCC).

The DFT precoder performs DFT precoding (eg, 12-point DFT) on the modulation symbols spread in each slot to produce a single carrier waveform. Referring to the figure, modulation symbols d_0, d_1,... Spread to slot 0; , d_L / 2-1 is DFT precoded into a DFT symbol, and the modulation symbols d_L / 2, d_L / 2 + 1,... , d_L-1 is DFT precoded with a DFT symbol. DFT precoding may be replaced with other corresponding linear operations (eg, walsh precoding).

In this specification, for ease of description, the orthogonal code is mainly described as a representative example of the spreading code. However, the orthogonal code may be replaced with a semi-orthogonal code as an example. The maximum value of the spreading code size (or spreading factor (SF)) is limited by the number of SC-FDMA symbols used for transmission of control information. For example, when five SC-FDMA symbols are used for transmission of control information in one slot, (semi) orthogonal codes w0, w1, w2, w3, and w4 of length 5 may be used for each slot. SF denotes a spreading degree of control information and may be related to a multiplexing order or antenna multiplexing order of a terminal. SF is 1, 2, 3, 4, 5,... It may vary according to the requirements of the system, and may be predefined between the base station and the terminal, or may be known to the terminal through DCI or RRC signaling.

The signal generated through the above process is mapped to a subcarrier in the PRB and then converted into a time domain signal through an IFFT. CP is added to the time domain signal, and the generated SC-FDMA symbol is transmitted through the RF terminal.

2. 4 PUCCH 통한 CSI (Channel State Information) 피드백 2. CSI (Channel State Information) feedback through 4 PUCCH

First, in a 3GPP LTE system, when a downlink receiving entity (eg, a terminal) is connected to a downlink transmission entity (eg, a base station), reception strength of a reference signal transmitted in downlink (RSRP: reference signal) Measurements on received power, reference signal received quality (RSRQ), etc. may be performed at any time, and the measurement results may be reported to the base station periodically or event triggered.

Each terminal reports downlink channel information according to the downlink channel situation through the uplink, and the base station uses appropriate downlink channel information received from each terminal to provide appropriate time / frequency resources for data transmission for each terminal. Modulation and coding scheme (MCS) may be determined.

The channel state information (CSI) may be composed of Channel Quality Indication (CQI), Precoding Matrix Indicator (PMI), Precoder Type Indication (PTI), and / or Rank Indication (RI). Depending on the transmission mode, all the CSI may be transmitted or only some of them may be transmitted. The CQI is determined by the received signal quality of the terminal, which can generally be determined based on the measurement of the downlink reference signal. In this case, the CQI value actually transmitted to the base station corresponds to an MCS capable of achieving maximum performance while maintaining a block error rate (BLER) of 10% or less in the received signal quality measured by the terminal.

In addition, the reporting method of such channel information is divided into periodic reporting transmitted periodically and aperiodic reporting transmitted at the request of the base station.

In the case of aperiodic reporting, the base station is configured to each terminal by a 1-bit request bit (CQI request bit) included in the uplink scheduling information given to the terminal, each terminal receives its own transmission mode Considering this, the channel information may be transmitted to the base station through the PUSCH. RI and CQI / PMI may not be transmitted on the same PUSCH.

In the case of periodic reporting, a period in which channel information is transmitted through an upper layer signal and an offset in a corresponding period are signaled to each terminal in subframe units, and the transmission mode of each terminal is considered in accordance with a predetermined period. Channel information may be delivered to the base station through the PUCCH. When data to be transmitted in uplink is simultaneously present in a subframe in which channel information is transmitted according to a predetermined period, in this case, the corresponding channel information may be transmitted through PUSCH together with data other than PUCCH. In the case of periodic reporting through the PUCCH, a limited bit (eg, 11 bits) may be used as compared to the PUSCH. RI and CQI / PMI may be transmitted on the same PUSCH.

If periodic reporting and aperiodic reporting collide within the same subframe, only aperiodic reporting can be performed.

In calculating the wideband CQI / PMI, the most recently transmitted RI may be used. RI in PUCCH CSI reporting mode is independent of RI in PUSCH CSI reporting mode, and RI in PUSCH CSI reporting mode is valid only for CQI / PMI in the corresponding PUSCH CSI reporting mode. Do.

Table 16 is a table for explaining the CSI feedback type and the PUCCH CSI reporting mode transmitted on the PUCCH.

Table 16

Referring to Table 16, four reporting modes of modes 1-0, 1-1, 2-0, and 2-1 according to CQI and PMI feedback types in periodic reporting of channel state information. Can be divided into

According to the CQI feedback type, it is divided into wideband CQI (WB CQI) and subband (SB CQI) and divided into No PMI and single PMI according to PMI transmission. In Table 11, No PMI corresponds to the case of open-loop (OL), Transmit Diversity (TD) and single-antenna, where a single PMI is a closed-loop (CL). closed-loop).

Mode 1-0 is when there is no PMI transmission and a WB CQI is transmitted. In this case, the RI is transmitted only in the case of open-loop (OL) spatial multiplexing (SM), and one WB CQI represented by 4 bits may be transmitted. If the RI is greater than 1, the CQI for the first codeword may be transmitted.

Mode 1-1 is when a single PMI and WB CQI are transmitted. In this case, four bits of WB CQI and four bits of WB PMI may be transmitted together with the RI transmission. In addition, when RI is greater than 1, 3 bits of WB spatial differential CQI may be transmitted. In 2 codeword transmission, the WB space differential CQI may indicate a difference value between the WB CQI index for codeword 1 and the WB CQI index for codeword 2. These difference values have one of a set {-4, -3, -2, -1, 0, 1, 2, 3} and can be represented by 3 bits.

Mode 2-0 is a case where there is no PMI transmission and a CQI of a UE selected band is transmitted. In this case, RI is transmitted only in case of open-loop spatial multiplexing (OL SM), and WB CQI represented by 4 bits can be transmitted. In addition, a Best-1 CQI may be transmitted in each bandwidth part (BP), and the Best-1 CQI may be represented by 4 bits. In addition, an indicator of L bits indicating Best-1 may be transmitted together. If the RI is greater than 1, the CQI for the first codeword may be transmitted.

Mode 2-1 is a case where a single PMI and a CQI of a UE selected band are transmitted. In this case, four bits of WB CQI, three bits of WB space differential CQI, and four bits of WB PMI may be transmitted together with the RI transmission. Additionally, four bits of Best-1 CQI may be transmitted in each bandwidth portion BP, and L bits of Best-1 indicator may be transmitted together. Additionally, when RI is greater than 1, three bits of Best-1 spatial differential CQI may be transmitted. This may indicate a difference between a Best-1 CQI index of Codeword 1 and a Best-1 CQI index of Codeword 2 in two codeword transmissions.

For each transmission mode, the periodic PUCCH CSI reporting mode is supported as follows.

1) Transmission mode 1: mode 1-0 and 2-0

2) Transmission mode 2: mode 1-0 and 2-0

3) Transmission Mode 3: Modes 1-0 and 2-0

4) Transmission Mode 4: Modes 1-1 and 2-1

5) Transmission Mode 5: Modes 1-1 and 2-1

6) Transmission Mode 6: Modes 1-1 and 2-1

7) Transmission Mode 7: Modes 1-0 and 2-0

8) Transmission mode 8: Modes 1-1 and 2-1 when the terminal is configured for PMI / RI reporting, Modes 1-0 and 2-0 when the terminal is configured not to perform PMI / RI reporting

9) Transmission mode 9: If the terminal has PMI / RI reporting configured and the number of CSI-RS ports> 1, modes 1-1 and 2-1, the terminal is configured not to report PMI / RI, or the CSI-RS port Modes 1-0 and 2-0 when Number = 1

The periodic PUCCH CSI reporting mode in each serving cell is set by higher layer signaling. Mode 1-1 is set to either submode 1 or submode 2 by higher layer signaling using the 'PUCCH_format1-1_CSI_reporting_mode' parameter.

The CQI report in a specific subframe of a specific serving cell in the SB CQI selected by the UE means measurement of one or more channel states of a bandwidth part (BP) which is a part of the bandwidth of the serving cell. The bandwidth part is indexed without increasing the bandwidth size in order of increasing frequency starting from the lowest frequency.

2.5 PUCCH를 통한 ACK/NACK 전송 방법2.5 ACK / NACK Transmission Method through PUCCH

In a situation where the terminal needs to simultaneously transmit a plurality of ACK / NACK signals corresponding to multiple data units received from the base station, in order to maintain a single carrier characteristic of the ACK / NACK signals and reduce the total ACK / NACK transmission power, the PUCCH resource Selection based ACK / NACK multiplexing method may be considered. With ACK / NACK multiplexing, the contents of ACK / NACK signals for multiple data units can be identified by a combination of one of the PUCCH resources and QPSK modulation symbols used for the actual ACK / NACK transmission. For example, if one PUCCH resource carries 4 bits and a maximum of 4 data units are transmitted (assuming that HARQ operation for each data unit is managed by a single ACK / NACK bit), The Tx node may identify the ACK / NACK result based on the transmission position of the PUCCH signal and the bits of the ACK / NACK signal as shown in Table 17 below.

Table 17

In Table 17, HARQ-ACK (i) indicates the ACK / NACK result for the data unit i. For example, i = 0, 1, 2, 3 when up to four data units are transmitted. In Table 17, DTX means that no data unit has been transmitted for the corresponding HARQ-ACK (i) or that a receiving node (Rx node) has not detected a data unit corresponding to HARQ-ACK (i).

Also,

Indicates a PUCCH resource used for actual ACK / NACK transmission. At this time, in the situation where four data units exist, a maximum of 4 PUCCH resources

,

And

May be assigned to the terminal.

Also, b (0) and b (1) mean two bits involved in the selected PUCCH resource. Modulation symbols transmitted on the PUCCH resource are determined according to the corresponding bits. For example, if the receiving node successfully receives four data units, the receiving node is a PUCCH resource.

We need to transmit two bits (1,1) using. Or, if the receiving node has received four data units but fails to decode for the first and third data units (ie, HARQ-ACK (0) and HARQ-ACK (2)), the receiving node has a PUCCH resource.

We need to send two bits (1,0) to the transmitting node using.

As such, by linking actual ACK / NACK contents with PUCCH resource selection and actual bit contents transmitted through PUCCH resources, ACK / NACKs for multiple data units can be transmitted using a single PUCCH resource.

Basically, if there is at least one ACK for all data units, in the ACK / NACK multiplexing method (see Table 17), NACK and DTX are connected together with NACK / DTX. This is because the combination of PUCCH resources and QPSK symbols is insufficient to cover all ACK, NACK and DTX situations. On the other hand, if there is no ACK for all data units (ie, if only NACK or DTX is present), a single NACK decoupled with DTX is defined as one HARQ-ACK (i). In this case, a PUCCH resource connected to a data unit corresponding to a single NACK may be reserved for transmission of multiple ACK / NACK signals.

2.6 상향링크 채널 코딩 방법2.6 Uplink Channel Coding Method

As described above, when the UE transmits UCI using PUCCH format 2, the UE performs (20, A) RM coding using a basic sequence shown in Table 12 of maximum CSI of 13 bits. On the other hand, when UCI is transmitted in PUSCH, (32, A) RM coding is performed using a basic sequence shown in Table 18 below for a maximum of 11 bits of CQI. Then, truncation or circular repetition is performed to match the code rate for the UCI to be transmitted in the PUSCH.

Table 18

Meanwhile, in LTE-A, PUCCH format 3 has been introduced to transmit up to 21 bits of UCI (eg, A / N and SR) bits. PUCCH format 3 may be configured to perform the same function as the CA PUCCH format (see Section 2.3).

In case of a normal CP, the UE may transmit a 48-bit coded bit using PUCCH format 3. Accordingly, when the number of UCI bits is 11 bits or less, the UE codes using (32, A) RM coding, but uses cyclic repetition to increase the coded bits to match the number of code bits in PUCCH format 3. If the UCI exceeds 11 bits, the basic sequence for the (32, A) RM coding shown in Table 18 is insufficient. Accordingly, the UE uses two (32, A) RM coding blocks as shown in FIG. 18 to make the UCI into two code bits (referred to as Dual RMs), and cut or reduce them to match the number of code bits in PUCCH format 3. Repeat the cycle. Thereafter, the terminal interleaves or concatenates the code bits generated by using dual (32, A) RM coding. 18 is a diagram for explaining dual RM coding.

When the UE transmits up to 21 bits of UCI through the PUSCH, when the number of UCI bits is 11 bits or less, the UCI bits are coded using (32, A) RM coding as in the existing LTE system, and the coded UCI A truncation or cyclic iteration is performed to match the code rate for transmission over the network. If the UCI exceeds 11 bits, the UE makes the UCI into two code bits using dual RM coding, and performs truncation or cyclic repetition to match the code rates for transmitting them on the PUSCH.

First, the bit configuration order for each content included in the UCI will be described. If the use of PUCCH format 3 is configured in the SR transmission subframe, the UE may transmit the SR and A / N bits in PUCCH format 3 or PUSCH. In this case, the terminal may preferentially arrange the A / N bits and arrange the SR after the A / N. FIG. 19 is a diagram for describing a method of outputting code bits interleaved when the dual RM coding of FIG. 18 is applied.

Referring to FIG. 19, it is assumed that data blocks having lengths A and B are inputs of (32, A) and (32, B) RM encoders, respectively. In this case, the code bits output through the (32, A) RM coder are rate matched to 24 bits, respectively, and A0, A1,... , A23 and B0, B1,... Is output as B23. At this time, two bits are sequentially output from two RM encoders, and A0, A1, B0, B1, A2, A3, B2, B3,... Generate the output bit streams of A22, A23, B22, and B23.

The output bit stream is modulated with QPSK, the first 24 bits of the bit string (12 QPSK symbol) are transmitted through the first slot, and the last 24 bits (12 QPSK symbol) of the bit string correspond to the second slot, according to the PUCCH format 3 transmission format. Is sent through.

3. MTC 단말의 HARQ-ACK 전송 방법3. HARQ-ACK transmission method of the MTC terminal

3.1 MTC 단말3.1 MTC terminal

LTE-A system (after Rel-12) is the next wireless communication system, considering the configuration of low-cost / low-end terminals mainly for data communication such as meter reading, water level measurement, surveillance camera utilization, and vending machine inventory reporting. have. In the embodiments of the present invention, such a terminal will be referred to as a machine type communication (MTC) terminal for convenience.

In the case of MTC terminal, since the amount of transmission data is small and up / down link data transmission and reception occur occasionally, it is efficient to lower the unit cost and reduce battery consumption in accordance with such a low data rate. The MTC terminal is characterized by low mobility, and thus has a characteristic that the channel environment is hardly changed. Currently, LTE-A considers such an MTC terminal to have wider coverage than the conventional one, and various coverage enhancement techniques for the MTC terminal are discussed for this purpose.

The MTC terminal may be installed in an area (e.g. basement, etc.) in which a transmission environment is worse than that of a legacy UE (ie, a general terminal). If a repeater or the like is installed for the MTC terminal, a lot of money may be spent on facility investment.

MTC is a communication method that performs communication between devices without human intervention. Smart metering may be considered as a typical application of MTC. This is an application technology that periodically transmits measurement information by attaching a communication module to a meter such as electricity, gas, or water.

Electricity, gas or water meters are usually operated by a battery built into the terminal. If the manpower is used to replace the battery of the MTC terminal, additional cost is required as much, so it is desirable to minimize the power consumption to use the battery as long as possible.

In the embodiments of the present invention, in order to increase the life of the battery used in the terminal, instead of transmitting HARQ-ACK every time data is transmitted in every downlink of the FDD system, a plurality of received in a plurality of downlink subframes Provided are methods for simultaneously transmitting HARQ-ACK for two data blocks. In this case, HARQ-ACK means information indicating whether the decoding of the data block success and / or failure (ACK / NACK).

3.2 HARQ-ACK 전송 타이밍3.2 HARQ-ACK Transmission Timing

The MTC terminal should transmit HARQ-ACK for data blocks received in a downlink subframe (DL SF). However, considering the characteristics of the MTC terminal, transmitting the HARQ-ACK in every subframe may reduce the power efficiency of the MTC terminal. Accordingly, the MTC terminal may consider transmitting HARQ-ACK for a predetermined number (N) of subframes.

For example, after the MTC terminal monitors PDCCH or E-PDCCH transmitted in N (> 1) DL SFs, if there is a data block for the MTC terminal, HARQ-ACK for the corresponding data blocks is N-sub. It can be configured to transmit at the same time at the HARQ-ACK transmission time for the frame.

Hereinafter, a method of determining HARQ-ACK transmission timing based on the FDD scheme will be described.

In the LTE / LTE-A system, the HARQ-ACK transmission time point of the UE is after 4 subframes from the subframe receiving the PDCCH including the control information (ie, DCI) for the corresponding data block. It is assumed that the MTC terminal monitors PDCCH / EPDCCH transmitted in N subframes. That is, the MTC terminal may transmit a HARQ-ACK after monitoring the monitoring interval consisting of N subframes. Accordingly, the MTC terminal may be configured to transmit HARQ-ACK after 4 SFs of the corresponding Nth SF, assuming that there is control information for the data block in the Nth transmitted PDCCH / EPDCCH.

If the control information (DCI) for the corresponding MTC terminal is not transmitted in the PDCCH / EPDCCH transmitted in the Nth subframe of the monitoring interval, the MTC terminal does not transmit the HARQ-ACK.

Since there is no HARQ-ACK transmission for the data blocks transmitted in the N DL SFs included in the monitoring interval (ie, since the UE transmits one HARQ-ACK for subframes included in the monitoring interval), The number of HARQ processes is preferably increased by N. In the FDD scheme of the LTE / LTE-A system, since the number of HARQ processes is 8, the number of HARQ processes applied to the MTC terminal in the embodiments of the present invention may be set to N + 8.

Hereinafter, a method of determining HARQ-ACK transmission timing based on a TDD scheme will be described.

When applying the TDD scheme, it may refer to the TDD UL / DL configuration. That is, the subframe transmitting the HARQ-ACK may be fixed based on the TDD UL / DL configuration. Table 19 below shows an example of a TDD UL / DL configuration.

Table 19

Referring to Table 19, since the DL / UL switching occurs in a 5 ms period, the UL / DL configuration 2 may configure a monitoring interval with four consecutive downlink subframes and one uplink subframe. That is, the MTC terminal may simultaneously transmit HARQ-ACK for DL data blocks (e.g., up to four data blocks) received up to that time in SF 2 designated as UL. For example, if the MTC terminal transmits HARQ-ACK in SF 2, the MTC terminal simultaneously performs HARQ-ACK on DL data transmitted in subframes before 8, 7, 6, and 4 subframes based on SF 2. Can transmit

The above-described embodiment has been described based on the UL / DL configuration 2. Therefore, as an aspect of the present embodiment, considering other UL / DL configurations, the number of SFs included in the monitoring interval may be set by the common multiple of HARQ processes corresponding to each UL / DL configuration.

Hereinafter, a method of determining HARQ-ACK transmission timing in an FDD-TDD carrier combining environment will be described.

When the TDD scheme is applied to a primary cell (PCell) in FDD-TDD carrier combining, a TDD UL / DL configuration may be referred to. In this case, a subframe in which HARQ-ACK is transmitted may be fixed.

As shown in Table 19, when considering the UL / DL configuration 2 in the TDD Pcell, the MTC terminal may simultaneously transmit HARQ-ACK for a data block received and decoded before a subframe designated by UL. For example, if HARQ-ACK is transmitted in subframe 2, the MTC terminal is HARQ for the data block transmitted in subframes before 8, 7, 6, 5, and 4 subframes based on subframe 2 May be configured to send an -ACK.

20 is a diagram for describing HARQ-ACK transmission timing by an MTC terminal.

Referring to FIG. 20, the base station informs the size (N) of the monitoring interval statically or semi-statically through higher layer signaling (for example, RRC or MAC, etc.), or physical layer signaling (for example, (E). PDCCH, etc.) may dynamically inform the size (N) of the monitoring interval (S2010, not shown).

The MTC terminal attempts to receive the (E) PDCCH and DL data within the configured monitoring interval (S2020, not displayed).

In FIG. 20A, it is assumed that the size N of the monitoring interval is set to the minimum period in which the (E) PDCCH is transmitted. That is, it is assumed that the (E) PDCCH is transmitted in the Nth SF. Accordingly, the MTC terminal may receive the (E) PDCCH in the last SF of the monitoring interval and then transmit the HARQ-ACK to the base station after x SF (eg, x = 4) (S2030a not displayed).

In FIG. 20 (b), it is assumed that (E) PDCCH and PDSCH are transmitted in n (n = <N) SFs within a monitoring interval. In this case, the MTC terminal decodes n SFs, and may transmit HARQ-ACK to the base station after x SF in the SF at which the monitoring interval ends (S2030b not displayed).

20 (a) and 20 (b), the MTC terminal transmits HARQ-ACK information on all SFs included in the monitoring interval to the base station, but (E) the base station is set to NACK for the SF in which the PDCCH is not transmitted. Can be sent to.

20 (c) shows a case in which no (E) PDCCH is transmitted in the monitoring interval. In this case, the MTC terminal may be configured not to transmit the HARQ-ACK after the monitoring interval (S2030b not displayed).

In FIG. 20, the UE may always simultaneously transmit HARQ-ACK for a fixed number of subframes (eg, a number set through higher layer signaling or a number of subframes included in a monitoring interval).

In FIG. 20, x SF through which HARQ-ACK is transmitted may vary according to an FDD scheme or a TDD scheme, and may vary according to the requirements of a service provider or a channel environment. In addition, the number of HARQ processes for the MTC terminal may be set to N + 8 subframes in consideration of the size of the monitoring interval.

3.3 HARQ-ACK 인코딩 방법3.3 HARQ-ACK Encoding Method

Hereinafter, HARQ-ACK encoding methods for transmitting HARQ-ACK by the MTC terminal will be described.

The number of HARQ-ACK bits may be determined according to the number of carrier-coupled component carriers (ie, serving cells), transmission modes (eg, MIMO or non-MIMO), and / or monitoring interval size N. FIG.

In this case, various HARQ-ACK encoding schemes may be considered according to the number of HARQ-ACK bits. For example, when the number of HARQ-ACK bits is 20 bits or less, a dual RM encoding scheme of PUCCH format 3 may be used.

If HARQ-ACK information is for data blocks received in N DL SFs in the monitoring interval, it is assumed that the transmission mode does not support MIMO transmission. In this case, up to N HARQ-ACK bits may occur.

If a data block for a corresponding MTC terminal is not transmitted to some SFs among N DL SFs in a monitoring interval, the HARQ-ACK bit for the corresponding partial SFs is preferably filled with information corresponding to NACK. This is to minimize the ambiguity that may occur at both ends of the transmission and reception when the MTC terminal misses receiving the PDCCH / EPDCCH. Because, if the terminal configures HARQ-ACK bits only for the SF with the data block actually received, if the missed PDCCH / EPDCCH generated in a particular subframe, the base station assumes the HARQ-ACK bit configuration and the HARQ transmitted by the terminal This is because the -ACK bit configuration is different, which can reduce the system efficiency.

Even when the transmission mode supporting MIMO is applied to the MTE terminal, the same method as described above may be applied. In the case of MIMO transmission, since up to two transport blocks can be transmitted simultaneously, HARQ-ACK of 2N bits can be assumed as an input payload of PUCCH format 3.

3.4 PUCCH 자원 설정 방법3.4 How to set up PUCCH resources

Hereinafter, when HARQ-ACK transmitted by the MTC terminal is transmitted through the PUCCH, methods for configuring a PUCCH resource will be described.

PUCCH format 3 was introduced to transmit HARQ-ACK for a plurality of downlink CCs in LTE-A system. However, in the MTC environment, since CA may not be supported according to MTC characteristics, the PUCCH format 3 is not supported for the MTC terminal according to the LTE-A system standard. However, since the MTC terminal simultaneously transmits HARQ-ACK for SFs included in the monitoring interval, a relatively large HARQ-ACK bit is likely to be used. Therefore, in the embodiments of the present invention, even if a single carrier is supported for the MTC terminal, it may be configured to transmit HARQ-ACK using PUCCH format 3.

PUCCH resources used by the MTC terminal to transmit PUCCH format 3 may be allocated through an upper layer signal. In addition, an index for the corresponding PUCCH resource (ie, an A / N resource indicator (ARI)) is transmitted to the MTC terminal through the DCI of the PDCCH / EPDCCH.

When CA is applied, the PUCCH resource index for PUCCH format 3 is transmitted by borrowing a transmit power control (TPC) command included in the DCI format. However, if no CA is applied, the TPC command should be used for PUCCH power control and thus the TPC command cannot be borrowed. Thus, to configure a PUCCH resource for PUCCH format 3, a new field or a combination of existing fields or fields may be defined within the DCI format.

For example, suppose a new field is defined. If four PUCCH resources are used, a new 2-bit field may be used to indicate the PUCCH resource. That is, the size of the new field may be determined according to the number of PUCCH resources.

Or, it may be assumed that a PUCCH resource is indicated by using an existing field. For example, one or a combination of a Modulation and Coding Scheme (MCS) field, a Redundancy Version (RV) field, and / or a Sounding Reference Signal (SRS) request field included in the DCI format may be used to indicate a PUCCH resource. .

For example, assuming that 64QAM or more is not supported for the MTC terminal, the MCS index may be reserved without using 13 MCS states. Therefore, in the DCI format 1 / 1A, one or more of the reserved state portion of the MCS field, the 2-bit RV field, and / or the 1-bit SRS request field may be combined and used as an A / N resource indicator. In the case of DCI format 2C, a combination of one or more of a reserved state portion of the MCS field, an MCS field (5 bits) for the second codeword, an NDI 1 bit, a 2 bit RV field, and a 1 bit SRS request field is A /. Can be used as an N resource indicator.

In this case, the MTC terminal may transmit HARQ-ACK using a PUCCH resource indicated by the most recently received PDCCH / EPDCCH among PDCCH / EPDCCH for scheduling PDSCH transmission.

In another aspect of the present embodiment, when the PDCCH / EPDCCH transmitted in the last SF (that is, the Nth) subframe of the monitoring interval includes scheduling information for the corresponding MTC terminal, the MTC terminal is a PUCCH from the CCE information of the PDCCH / EPDCCH Resources can be inferred implicitly. Accordingly, the MTC terminal may transmit a plurality of HARQ-ACK information through the inferred PUCCH resource.

For example, when the PDSCH scheduling information for the MTC terminal is included in the PDCCH / EPDCCH transmitted in the Nth SF of the monitoring interval, the MTC terminal uses HARQ-ACK information through the PUCCH resource inferred from the CCE information for the PDCCH / EPDCCH. Can be transmitted simultaneously.

If the PDCCH / EPDCCH is not transmitted in the last Nth SF of the monitoring interval, the UE may transmit HARQ-ACK information through the PUCCH resource configured in the higher layer.

3.5 전력 제어3.5 power control

The TPC command for PUCCH transmission is transmitted on PDCCH / EPDCCH. Therefore, the MTC terminal may adjust the PUCCH transmission power according to the PUCCH TPC command included in the PDCCH / EPDCCH most recently including scheduling information for the PDSCH.

Alternatively, the MTC terminal may adjust the PUCCH transmission power according to the TPC command transmitted in DCI format 3 / 3A. In this case, the PUCCH transmission power may be adjusted according to the payload size of the PUCCH format 3. The payload size of the PUCCH format 3 may be the size N or 2N bits of the monitoring interval according to a transmission mode supporting MIMO. Accordingly, the PUCCH transmit power can be adjusted assuming payload size N or 2N.

4. 구현 장치4. Implement device

A UE may operate as a transmitting end in uplink and a receiving end in downlink. In addition, an e-Node B (eNB) may operate as a receiving end in uplink and a transmitting end in downlink.

That is, the terminal and the base station may include

transmitters

2140 and 2150 and

receivers

2150 and 2170 to control the transmission and reception of information, data and / or messages, respectively. Or

antennas

2100 and 2110 for transmitting and receiving messages.

In addition, the terminal and the base station may each include a

processor

2120 and 2130 for performing the above-described embodiments of the present invention, and

memories

2180 and 2190 capable of temporarily or continuously storing the processing of the processor. Can be.

Embodiments of the present invention can be performed using the components and functions of the above-described terminal and base station apparatus. For example, the process of the MTC terminal may control the receiver to receive an upper layer signal or a physical layer signal including setting information on the size of the monitoring interval. In addition, the process of the MTC terminal may attempt to receive the (E) PDCCH during the set monitoring interval, and transmit the HARQ-ACK to the base station by controlling the transmitter after a predetermined SF from the SF after the monitoring interval. The process of the base station may control the transmitter to transmit the above-described higher layer signal or physical layer signal to the terminal, and control the receiver to receive the HARQ-ACK transmitted from the terminal. A method of encoding HARQ-ACK, a method of allocating resources, and a method of controlling transmission power may refer to Sections 1 to 3 above.

The transmitter and the receiver included in the terminal and the base station include a packet modulation and demodulation function, a high speed packet channel coding function, an orthogonal frequency division multiple access (OFDMA) packet scheduling, and a time division duplex (TDD) for data transmission. Packet scheduling and / or channel multiplexing may be performed. In addition, the terminal and the base station of FIG. 21 may further include a low power radio frequency (RF) / intermediate frequency (IF) unit.

Meanwhile, in the present invention, the terminal is a personal digital assistant (PDA), a cellular phone, a personal communication service (PCS) phone, a GSM (Global System for Mobile) phone, a WCDMA (Wideband CDMA) phone, an MBS. A Mobile Broadband System phone, a hand-held PC, a notebook PC, a smart phone, or a Multi Mode-Multi Band (MM-MB) terminal may be used.

Here, a smart phone is a terminal that combines the advantages of a mobile communication terminal and a personal portable terminal, and may mean a terminal incorporating data communication functions such as schedule management, fax transmission and reception, which are functions of a personal mobile terminal, in a mobile communication terminal. have. In addition, a multimode multiband terminal can be equipped with a multi-modem chip to operate in both portable Internet systems and other mobile communication systems (e.g., code division multiple access (CDMA) 2000 systems, wideband CDMA (WCDMA) systems, etc.). Speak the terminal.

Embodiments of the invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs). Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. For example, software code may be stored in the

memory units

2180 and 2190 to be driven by the

processors

2120 and 2130. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. In addition, the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship or may be incorporated as new claims by post-application correction.

Embodiments of the present invention can be applied to various wireless access systems. Examples of various radio access systems include 3rd Generation Partnership Project (3GPP), 3GPP2 and / or IEEE 802.xx (Institute of Electrical and Electronic Engineers 802) systems. Embodiments of the present invention can be applied not only to the various radio access systems, but also to all technical fields to which the various radio access systems are applied.

Claims

In a method of transmitting an acknowledgment signal (HARQ-ACK) by the MTC terminal in a wireless access system supporting Machine Type Communication (MTC),

Monitoring a physical downlink control channel (PDCCH) in a monitoring interval consisting of N subframes;

Receiving at least one PDCCH in the N subframes;

Receiving at least one physical downlink shared channel (PDSCH) in the N subframes; And

And transmitting a HARQ-ACK for the N subframes in an x-th subframe after the subframe in which the monitoring interval ends.
The method of claim 1,

In the subframe in which the at least one PDCCH is received, the HARQ-ACK is configured with ACK or NACK information for a received physical downlink shared channel (PDSCH),

The HARQ-ACK transmission method, wherein the HARQ-ACK is configured with NACK information for a subframe in which the at least one PDCCH is not received.
The method of claim 2,

Receiving a higher layer signal including information on the size N of the monitoring interval,

The number of HARQ processes for the MTC terminal is set in consideration of the size N of the monitoring interval, HARQ-ACK transmission method.
The method of claim 2,

The at least one HARQ-ACK is transmitted through a physical uplink control channel (PUCCH) format 3,

HARQ-ACK transmission method, which is assigned only a single carrier to the MTC terminal.
The method of claim 4, wherein

When the PDCCH is transmitted in the last subframe of the monitoring interval, the HARQ-ACK transmission in which the at least one HARQ-ACK is transmitted through the resources of the physical uplink control channel (PUCCH) inferred based on the CCE information for the PDCCH. Way.
The method of claim 4, wherein

If the PDCCH is not transmitted in the last subframe of the monitoring interval, the at least one HARQ-ACK is transmitted through a physical uplink control channel (PUCCH) configured in a higher layer, HARQ-ACK transmission method.
The MTC terminal transmitting the acknowledgment signal (HARQ-ACK) in a wireless access system supporting Machine Type Communication (MTC),

transmitter;

receiving set; And

A processor operatively connected to the transmitter and the receiver, the processor configured to transmit the HARQ-ACK;

The processor is:

Monitoring a physical downlink control channel (PDCCH) in a monitoring interval consisting of N subframes;

Control the receiver to receive at least one PDCCH in the N subframes;

Receiving at least one physical downlink shared channel (PDSCH) in the N subframes; And

And transmitting a HARQ-ACK for the N subframes in an x-th subframe after the subframe in which the monitoring interval ends.
The method of claim 7, wherein

In the subframe in which the at least one PDCCH is received, the HARQ-ACK is configured with ACK or NACK information for a received physical downlink shared channel (PDSCH),

The HARQ-ACK is configured with NACK information for a subframe in which the at least one PDCCH is not received.
The method of claim 8,

The processor is further configured to control the receiver to receive a higher layer signal including information about the size N of the monitoring interval,

The number of hybrid automatic retransmission (HARQ) processes for the MTC terminal is set in consideration of the size N of the monitoring interval, MTC terminal.
The method of claim 8,

The at least one HARQ-ACK is transmitted through a physical uplink control channel (PUCCH) format 3,

Only a single carrier is allocated to the MTC terminal, MTC terminal.
The method of claim 10,

When the PDCCH is transmitted in the last subframe of the monitoring interval, the at least one HARQ-ACK is transmitted through the resources of the physical uplink control channel (PUCCH) inferred based on the CCE information for the PDCCH.
The method of claim 10,

If the PDCCH is not transmitted in the last subframe of the monitoring interval, the at least one HARQ-ACK is transmitted through a physical uplink control channel (PUCCH) configured in a higher layer, MTC terminal.